Ex turpi causa: when illegality bars a claim

The maxim “ex turpi causa non oritur actio” prevents a claim being made where it is in some way tainted by the claimant’s illegal act or other contravention of public policy rules. Although the availability of this defence arises in a variety of contexts, its scope has yet to be clearly defined. Matters have become more complex by a series of conflicting Supreme Court decisions. Brief mention of those will be made later.

The most recent motor insurance case to consider the problem is McCracken v Smith and Others [2015] EWCA Civ 380. The leading judgment was given by Richards LJ. Underhill and Christopher Clarke LJJ agreed with his views.